Field of the Invention
The invention relates to a light-emitting device, and more particularly, to a light-emitting diode (LED) and a manufacturing method thereof.
Description of Related Art
As semiconductor techniques advance, the current light-emitting diode now has characteristics such as high brightness and high color rendering properties. Moreover, the light-emitting diode has advantages such as power saving, small size, low voltage drive, and no mercury, and therefore the light-emitting diode is extensively applied in areas such as display and illumination.
However, at this development stage of the LED, how to increase the luminous efficiency of the LED is one of the focuses in the field of LED. In general, the luminous efficiency of the LED is related to the uniformity of current distribution on the LED surface. Specifically, when a known LED is to be operated, a driving voltage is provided to two electrodes to drive electrons and electron holes to flow between the two electrodes, and to recombine the two in a quantum well layer to emit photons. Since the current (or electron flow) of an external input enters the quantum well layer along the path of smallest resistance, the resistance of the current (or electron flow) is related to the locations of the electrodes. For instance, the current (or electron flow) moves to the portion of the quantum well layer closest to the corresponding electrode from the portion of the electrode closest to the quantum well layer. Due to the above characteristics, the current on the surface of the LED cannot readily achieve uniform distribution, such that the phenomenon of nonuniform current distribution occurs in the light-emitting region. As a result, the overall luminous efficiency of the LED is poor. Therefore, how to solve the issue is an important topic for those skilled in the art.